Learning and Memory Flashcards
What parts of the brain were removed in H.M.
Medial temporal lobe
What effects on memory were observed post surgery in H.M.
- Anterograde amnesia: the inability to form new memories
- Very limited capacity of short term memories
Declarative memory
Memory that we can declare to others such as facts and information acquired through learning
Procedural memory
Things you learn by doing, such as muscle memory
H.M.’s performance on the mirror tracing task
H.M. would make less errors as he kept practicing tracing a shape in a mirror even though he did not remember doing this task
Delayed non-matching-to-sample task
Participant must choose the stimulus not previously seen, testing object recognition memory
Lesion of what brain structures lead to the most impairment on delayed non-matching-to-sample task
Entorhinal, parahippocampal, perirhinal cortex as well as the hippocampus
Brain region responsible for sense of familiarity
Perirhinal cortex
Brain region responsible for recognition of an object
Hippocampus
Diencephalon structures implicated in formation of declarative memories
Medial thalamus and mamillary bodies
Episodic memory
Particular incidents or particular time and place
Semantic memory
Recollection of a word, concept, or number
Steps in current model of declarative memory formation
- Sensory processing in the cortex
- Sent to medial temporal lobe (parahippocampal, entorhinal, perirhinal cortex)
- Processed in the hippocampus
- Medial diencephalon (mamillary bodies)
- Declarative memory storage in the cortex
What effect do medial temporal lesions have on priming tasks
People with medial temporal lesions are…
- Worst at free recall
- Better at cued recall (only given parts of the word i.e dis & che)
- Best at completion (given space for missing letters i.e. dis____ & che___)
Classical conditioning
Eliciting a response (salivating) through pairing an unconditioned stimulus (food) with a conditioned stimulus (bell)
Delay conditioning
Conditioned stimulus occurs then some time later (the delay), the unconditioned stimulus occurs while CS is still happening and the two terminate together
Effect of medial temporal lobe amnesia on delay conditioning
The conditioning response is intact
Trace conditioning
Conditioned stimulus is presented then ends, then after an interval of time the unconditioned stimulus is presented then ends
Effect of medial temporal lobe amnesia on trace conditioning
The conditioned stimulus is hard to remember due to no overlap, which leads to impaired conditioning
Associative learning
Two unrelated events become related through conditioning
Operant conditioning
A form of associative learning where consequences influence likelihood of an act being performed
Cognitive map
Mental representation of spatial relationships
Place cells
Neurons in the hippocampus that fire when in a certain location
Grid cells
Neurons that fire when an animal crosses an intersection of an abstract grid map
- Work as an innate sense of latitude and longitude
What type of memory is impaired in medial temporal lobe amnesia and what type is intact
Impaired: declarative memory (semantic memory, trace conditioning, spatial memory)
Intact: non-declarative memory (priming, skill learning, delay conditioning)
Working memory
Can remember working memories well, but only for a short period of time
What part of the brain is involved in working memory
Prefrontal cortex
Long term memory
Takes longer to remember well due to long term changes such as protein synthesis
Consolidation
The process of rehearsing or using information to commit it to long term memory
Encoding of declarative memories
An event has coactive neurons with various interlinked sensory attributes which each project to the corresponding brain structures
Retrieval of declarative memories before consolidation
A retrieval cue activates hippocampus which then activates sensory brain structures associated with event
Retrieval of consolidated memory
A retrieval cue no longer involves the hippocampus and instead activates sensory brain structures in the cortex
Experiment involved in spatial location recognition memory
Study phase - rat goes into any 8 arms
Test phase - Doors block all but 2 arms: arm entered in study and one random arm
Correct response - Entering the arm previously entered in study phase
Lesioning what brain region leads to impairment in spatial location recognition tasks?
Hippocampus
Experiment involved in response recognition memory
Rats receive food only if they turn to the same side of their body in both parts of the experiment
Lesioning what brain region leads to impairment in response recognition tasks?
Striatum
What is a double dissociation experiment
When two related mental processes function independently of each other
Explain the double dissociation of the hippocampus and the striatum in terms of spatial and response memory
Spatial memory: hippocampus does poorly while the striatum does well
Response memory: hippocampus does well while the striatum does poorly
Evidence of competition among memory systems
In a task that tests both place and response learning, inactivating the hippocampus leads to better performance in response tasks (controlled by striatum) and vice versa
Brain region involved in priming
Neocortex
Brain region involved in procedural memory
Striatum, motor cortex, cerebellum
Brain region involved in classical conditioning
Amygdala and cerebellum
How does our brain account for the instability of system that is highly plastic
Some areas of our brain are very plastic while some are more stable and less subject to change
Hebbian theory
Neurons that fire together, wire together
- Leads to increase in synaptic efficiency
Types of conditions rats can be placed in
Standard condition: housed in small groups in standard lab cages
Impoverished condition: housed individually in standard lab cages
Enriched condition: housed in large social groups in cages containing various toys and other features
What effect does the rat’s condition have on apical dendrites
No change
What effect does the rat’s condition have on basal dendrites
Rats placed in enriched conditions have more branching on the 3rd order of branch (as well as overall)
Short term changes in neurons that lead to increased PSP
- More NT released from presynaptic neuron
- Larger receptive field on postsynaptic neuron
- Synapse enlarges on either side of synapse
Long term/more stable changes in neurons
- Interneuron affects polarization of presynaptic terminal leading to increased released of NT
- Formation of new synapses
- Rearrangement of synaptic input
Pathway of information through hippocampus
- Input to hippocampus through Entorhinal cortex
- Neurons from Entorhinal cortex synapse onto dentate gyrus
- Mossy fibers (axons from granule cells) connect the dentate gyrus and CA3 pyramidal cells
- Schaffer collaterals connect CA3 and CA1 pyramidal cells
Tetanus
Intense volley of action potentials
What happens to EPSP in Input 1 when a tetanus is given to Input 1 followed by baseline voltage
After the tetanus, the amplitude of the EPSP is much higher than before even when same level of input is given before and after tetanus
What happens to EPSP in Input 2 when a tetanus is given to Input 1 followed by baseline voltage
No change in EPSP is observed, demonstrating LTP is input specific
NMDA receptors during normal synaptic transmission
Inactive due to magnesium blockage
AMPA receptors during normal synaptic transmission
Depolarize the cell when activated
How is the magnesium block in NMDA released
A strong depolarization releases magnesium from the NMDA receptor leading to influx of calcium
What effect does calcium have in the synapse
Increased [Ca] leads to activation of protein kinases, which adds AMPA receptors to the postsynaptic membrane as well as enhanced NT release
How is the synapse affected after induction of LTP
More neurotransmitter is released and there are more AMPA receptors in the postsynaptic membrane, which leads to rapid and stronger responses
Steps in neurochemical cascade during LTP induction
- Rapid influx of calcium
- High [calcium] activate protein kinases which activate protein
- CREB bind to cAMP which regulates transcription of many genes
- Changes in transcription -> change in protein, some of which are necessary to maintain LTP
Conditioned stimulus in coincidence detector
- The weak synapse and where the change takes place
- Where NMDA receptors are
- Conditioned stimulus doesn’t depolarize cell enough to activate NMDA receptors
Unconditioned stimulus in coincidence detector
- A strong stimulus that works on the motor neuron
How does the coincidence detector work
- Motor neuron in system releases neurotransmitter
- Unconditioned stimulus causes strong depolarization
- Occurrence of both events at the same time causes unblocking of NDMA receptor at weak synapse and influx of calcium
- Leads to pairing of conditioned and unconditioned stimulus
Aplysia sea slug
Has a siphon through which it draws water, and if you squirt water at the siphon it retracts its delicate gills
Aplysia as a model for memory formation
Changes in the synapse between gill motor neuron and a sensory cell that detects the squirt of water lead to habituation to the squirts of water
- Release less transmitter and retracts some synaptic terminals
What occurs before training in eyeblink conditioning
- Puff of air on eye leads to reflexive blinking
- Information about puff of air is sent to the cerebellum (which in the future can trigger eye blinking through cranial nerves)
What occurs during training in eyeblink conditioning
- Bell is sounded when puff of air is administered, leading to pairing of the two stimuli
- Info about the bell is sent to cerebellum where it converges with impulses of air puff on specific neurons
- Repeated pairing leads to strengthening on these synapses
What occurs after training in eyeblink conditioning
- Sound of the bell drives cerebellum to trigger an eye blink thru cranial nerves even if no air puff occurs (conditioned response)
- Repeated presentation of the bell without air puff leads to extinction
